Neither is a scenario you want to have happen to your batteries as it will probably shorten the lifespan of both and could create a potentially create a dangerous situation if one battery gets severely overcharged. Which is not good.
What Is Wrong With Wiring Batteries In Parallel Solar
What happens when you connect batteries in parallel. One 12 volt 10ah battery one 12 volt 10ah battery connected in parallel equals 12 volts and 20 amps. The basic concept is that when connecting in parallel you add the amp hour ratings of the batteries together but the voltage remains the same. Small voltage difference between these two batteries can balanced but if voltage difference is high it may destroy lower voltage battery. Two 6 volt 45 ah batteries wired in parallel are capable of providing 6 volt 9 amp hours 45 ah 45 ah. When you connect two identical batteries in parallel you double the output capacity while keep the output voltage the same as either battery. In short when two non identical batteries are connected in parallel current will flow from higher voltage battery to lower voltage battery.
When you connect two batteries in parallel you are able to double the capacity amperage rating while maintaining the same voltage. Connecting in parallel increases amp hour capacity only. In the other case if two identical batteries are connected in series the output voltage is doubled but the output capacity is kept the same as either battery. Wiring batteries together in parallel has the effect of doubling capacity while keeping the voltage the same. The same is also true of batteries that are identical in every way except that one battery is older than the other.
Gallery of What Happens When You Connect Batteries In Parallel
